Hi Jamie,
long time no hear - how is the tank?
I am not sure if I understand: did your light bulb/ lamp itself shorten out, or the ballast? The ballast, if that shorted out, most likely drives two lamps, so, both lamps would be out.
If you are looking for a single lamp I can give you one so you can try out if that is it and then you can order one. They are only about $18.00 each.